Justification:
This stork has been uplisted to Endangered because recent population estimates from its stronghold in Sumatra suggest that it is undergoing a very rapid ongoing population decline owing to intense hunting pressure at nesting colonies, human disturbance and the rapid loss and conversion of coastal habitat.

Mycteria cinerea occurs in Cambodia, Peninsular Malaysia and the islands of Sumatra, Java, Bali, Sumbawa, Sulawesi and Buton, Indonesia (BirdLife International 2001). The vast majority are in Indonesia, with perhaps 1,600 birds on Sumatra in 2008-2009 (down from estimates of c.5,000 in the late 1980s) and <500 in west Java (Iqbal et al. in prep.) There are records from elsewhere in Indonesia, including Sulawesi, Bali, Lombok and Sumbawa (Birdlife International 2001), but little recent information and no known breeding colonies. There are estimated to be c.10-20 pairs at Tonle Sap lake, Cambodia (J. Eames in litt. 2006), with 17 pairs in 2010 (van Zalinge et al. 2011). It is a vagrant to Thailand and Vietnam. Numbers have apparently declined in most parts of its range, with counts from Malaysia falling consistently from over 100 individuals in 1984, to fewer than 10 birds in 2005 (Malaysian Nature Society 2005, Li et al. 2006), and only a single wild bird was recorded in the Matang Mangrove Forest in 2010 (DWNP 2010). On Sumatra, although good numbers can still be found at some sites in South Sumatra province it has apparently declined considerably (Li et al. 2006, M. Iqbal in litt. 2006, Iqbal and Hasudungan 2008, Iqbal et al. in prep.). The largest counts in recent years have included 500 birds in 2005 in Muara Padang subdistrict, South Sumatra (Iqbal & Hasudungan 2008), a breeding colony estimated to contain 100-115 nests at Kumpai lake (South Sumatra) in 2008 (Iqbal et al. 2008), and a maximum count of 278 birds at Bagan Percut (North Sumatra province) in 2005 (Shepherd & Giyanto 2009).

The global population was previously thought likely to total fewer than 5,000 individuals, roughly equating to 3,300 mature individuals, based on estimates of c.5,000 individuals in Sumatra in the late 1980s (Silvius and Verheugt 1989) and 100-150 individuals in Java (M. Silvius in litt. 2002), plus 10 birds in Malaysia and 20-40 in Cambodia. Recent estimates put the global population far lower, at around 2,200 birds, based on totals of c.1,600 in Sumatra (c.75 individuals in Aceh province, c.500 North Sumatra province, c.350 Riau province, c.100 Jambi province, c.500 South Sumatra province and c.75 Lampung province), c.500 individuals, but possibly fewer, on Java, and <100 birds on the mainland of South-East Asia (Iqbal et al. in prep). This roughly equates to 1,500 mature individuals.

It is a predominantly coastal resident in Indonesia and Malaysia, inhabiting mangroves and adjacent, less saline, swamps. It forages on tidal mudflats, in saline pools, freshwater marshes, fishponds and rice-fields. The species has been documented as eating fishes, prawns and crabs (Iqbal et al. 2008, 2009). Birds only occur inland in flooded forest around Tonle Sap lake in Cambodia, from where they disperse in the wet season, possibly to the coast (van Zalinge et al. 2011).

In Indonesia, tidal forests including mangroves are threatened by agricultural conversion and development schemes, particularly large-scale fish farms and tidal rice cultivation, logging and related disturbance; as a result, mangrove clearance has been rapid. Hunting for food and trade also exerts a significant pressure throughout its range. In 1989, 40-50 birds were shipped to zoos across South-East Asia. Persecution and disturbance at nesting colonies are thought to be the main threat in Malaysia. The same is said to be the case in South Sumatra, where local people hunt the species and take chicks and eggs for food and domestication (Iqbal et al. 2008), and harvesting of chicks was still taking place in 2008-2009 (Iqbal et al. in prep). In Cambodia, exploitation of waterbird eggs and chicks and snaring of adults, for food and trade, coupled with the increasing likelihood of conversion of flooded forest for agriculture, threaten the Tonle Sap lake breeding colony, although the small population here is currently well-protected. Poisoning may be another significant, as yet unquantified, threat. Hybridisation with with Painted Stork M. leucocephala has occurred at Ang Trapeang Thmor Sarus Crane Reserve, Cambodia in 2007 and 2008, as well as in captive populations, including free-flying birds (Eames 2007, Yong D. L. in litt. 2011, J. C. Eames in litt. 2011). The potential spread of Milky and Painted Storks from an unringed and full-winged colony at the National Zoo in Kuala Lumpur is a potential threat to pure wild stock (D. Bakewell in litt. 2013). These Painted Storks have now reached the Selangor coast, and if they move northwards cross-breeding with the Milky Storks in Matang could be a possibility - hybrids have already been reported in the greater Klang Valley (Y. C. Aik in litt. 2012). Free-flying Painted and Milky Storks also occur at Singapore Zoo, and hybridisation has apparently produced reproductively viable offspring (Yong D. L. in litt. 2011), raising the possibility that these birds could cross to Sumatra and mix with key Milky Stork populations.

Conservation Actions UnderwayCITES Appendix I. Colonies are located in at least five protected areas in Sumatra and one each in Java, Sulawesi and Peninsular Malaysia. At Tonle Sap lake, Cambodia, large waterbird breeding colonies are designated core areas of the Biosphere Reserve, are proposed as Ramsar Sites, and have received active monitoring and improved enforcement of regulations since 1997. In Cambodia, posters depicting the species are used in promoting public environmental awareness. The Milky Stork Breeding and Re-introduction Programme, run by a number of stakeholders, coordinates the captive breeding and release of individuals into the Kuala Selangor Nature Park, Malaysia (Malaysian Nature Society 2005). Efforts are underway to effect legislative protection of the Matang Mangrove Forest Reserves in Perak, Malaysia, and advocacy is being used as an additional tool in the species's conservation (Malaysian Nature Society 2005). Successful breeding in captivity, survival of free-flying released birds, and attempted nesting in the wild by captive-bred individuals has been achieved in Malaysia (Malaysian Nature Society 2005). A total of 31 birds were released between 2007-2010, and successful hatching of two chicks occurred in 2010 (DWNP 2010). Surveys of the population in Sumatra took place in 2008-2009 (Iqbal et al. in prep).